[unreadable] Childhood obesity has become a major public health concern. One of the key gaps in understanding childhood obesity is the lack of an accurate assessment of the intensity of children's physical activities in their social context. Although extensive work along these lines has been conducted for adults, little has been conducted for children. In large-scale surveys, social and behavioral scientists collect information on children's participation in socially meaningful categories. But these measures do not capture the intensity of physical activity involved. Exercise physiologists and obesity researchers have developed self-report measures of the type, duration, and intensity of children's physical activity; however, they do not collect information on the social context. The specific aim of this proposed project is to convene a network of scientists conducting research from multiple perspectives, that of social and behavioral science, exercise physiology, and public health and nutrition, to study children's activities. This network would focus upon children of ages not typically studied, those 3-5, as well as those 6-12, and would consider children of diverse ethnic backgrounds. The objectives address the four areas of research design, measurement, data collection techniques, and analytic methods. Our specific aims are: 1) To evaluate the current state of measurement and data collection on physical activity and associated societally meaningful categories of activity, 2) To evaluate how to link the social and behavioral scientific approaches to physical activity and the physiological approaches to determining activity levels and energy expenditures, and 3) To conduct pilot testing to explore how to incorporate such techniques and to determine the cost and effectiveness of recommended methods/equipment for large-scale studies. [unreadable] [unreadable]